The invention relates generally to the treatment of articles so as to separate the material forming one part thereof from the material forming another part thereof. Of particular interest to the invention is the treatment of metal-synthetic resin composites so as to effect separation of the metal and the synthetic resin.
The problem of separating the metallic and synthetic resin components of composites made up of these substances is one which arises frequently. Examples of such composites include screw caps, which are normally provided with a bonded, relatively inaccessible interior layer of synthetic resin for sealing purposes, particularly for applications in carbonated beverage vending machines. In addition, there are many other metal-synthetic resin composite systems which are used in various phases of industry. It is often desired to recover the metallic component of such composites. Since the synthetic resin layer or coating is mostly, or at least quite often, composed of polyvinylchloride, it is not possible, on evironmental grounds, to burn the synthetic resin layer in order to recover the metal. The reason for this resides in the fact that combustion of polyvinylchloride releases chlorine compounds, which are mostly in the form of hydrogen chloride, thus leading to pollution of the environment.
Consequently, it is desirable to find some other manner of separating the metallic and synthetic resin components of composites made of these substances.